Electric-lamp socket



F. E. JoHNsoN ELECTRIC LAMP SOCKET May 25 1926.

Filed August 4, 1925 Patented May 25, v1926.

FRANK E. JOHNSON, 0F NEW l u1,586,367 'UNITED STATES PATENToFi-ica BEDFORD, MASSACHUSETTS, ASSIGNOR TO JOHN I.

PA'ULIDING, INC., OF NEW BEDFORD, MASSACHUSETTS, A CORPORATION 0F MASSA- CHUSETTS.

. ELECTRIC-LAMP sooner.

This invention relates to electric lamp sockets and more particularly to electric lamp sockets of the two part type comprising a cap and a shell provided with interlocking means for holding the two parts is assembled relation and for preventing rela` tive rotary movement.

Heretofore, in the simpler forms of such lamp sockets, it has been customary to provide the shell-member of the socket with one or more outwardly extending projections or latches at opposite points adapted to interlock with openings in the flange. of the cap-member. In order to avoid dillicu'lty in gettingthe key-slot in the right position when the socket is assembled, the flange of the, cap has been provided with openings around its entire circumference thereby permitting the shell to be inserted in the cap in.A any relative rotary relation. of the two parts. -The provision of openings around the entire circumference' of the cap, however, weakens it to such an extent that it may become warped inthe assembling process and thereby becomes useless and also detracts from its attractive appearance. To strengthen the cap and to add to its attractiveness, it has been customary to provide the cap with an outer smooth ring concealing said openings and giving 1t a smooth exterior. This construction, however, materially increases the cost of production which is an important consideration in the manufacture of such articles. Furthermore, in such construction, it has generally been found necessary for preventing relative rotary movement of the parts to provide means separate from and-in addition to the latching means which has also increased the number of operations necessary for and the expense of manufacture.

'The main object of my invention is the provision in a two part lamp socket of simple and eicient means for lockingthe two parts thereof together against both separation and relative rotary movement.

Another object of the invention is the provision of interlocking means so constructed that the socket is not weakened nor is its attractiveness Ain appearance sacrificed.

A further object is the provision `of a socket which is so'constructed that it can be manufactured in the minimum number of operations and at a very low cost.

l Other objects y of the invention will be more specifically set forth and described hereinafter.

In the drawings, illustrating the preferred form Aof the invention, Figure 1 is a view in perspective of a lamp socket constructed in accordance therewith, and shown in disassembled condition, the cap being viewed from below and the shell from above; Figure 2 is a vertical sectional view on an enlarged scale of the interlocking means showing the two parts in locked condition; Figure 3 is a. similar View of the same parts but showing them in an unlocked condition under the pressure of a thumb in dotted outlines on the shell preparatory to being se arated; Figure 4 isa horizontal sectional view showing the engaging portions oi' the cap and shell and illustrating the locking relation therebetween to prevent relative rotary movement; and Figure 5 is a plan view of the top edge of the shell illustrating the location of the latches on that member.

One of the important and novell features of my invention consists in providing a socket cam member having an imperforate lower portion or flange in which a series of inwardly extending projections are formed for locking the end of the shell within the cap. The projections are preferably formed by making a series of short cuts around the lower portion or flange of the caps and then indenting the material adjoining each cut between the cut and the edge ot the cap to form an inwardly extending projection, the cut end of which serves as a locking shoulder. The main advantage of this construction is that the cap is not at all weakened by the forming of the locking projections thereinosince no part of it is'perforated and it thereby becomes unnecessary to add any means, such as the ring now used, for reenforcing the lower portion or flange of the cap. This eects a material saving in the4 cost of production. Furthermore, the indentation of the locking projections causes a play of light and shade on that portion of the cap and enhances the attractiveness and ornamental' character of its appearance.

Referring to the drawings, illustrating the preferred `form of my invention, l0 designates the shell and 12 the cap of a two-part socket, the shell being provided with the usual key-slot le. The upper end of the shell is provided around its entire circumference with a series of longitudinally `depressed portions 16 in the nature of corrugations and spaced apart to leave intermediate raised or elevated portions 18. lThe depressed and raised portions are substantially flat but are connected together by inclined walls 20 so that angular shoulders are formed' on the sides of the elevated portions 18.

The lower portion or flange.; of the cap around its entire circumference is provided with a series of partially sheared inwardly pressed projections 22 extending upwardly (Fig. 1) and corresponding in number to the number of depressed portions in the shell. Preferably, the projections 22 are each formed by making a straight cut 25 parallel to the edge of the cap and then pressing the material inwardly the cut end of the inwardly pressed material or projection serving as a latching surface. Each projection is flat and its sides are connected to the iange of the cap by the walls 23.

Since each projection is an integral part of the cap and is merely pressed inwardly with the cut at -its end only, the cap is not weakened thereby and preserves its initial strength. In width the projections are slightly less than the depressions 16 in the shell and the intermediate portions 24 slightly more than the similar portions 18 in the shell and in consequence when the two parts of the socket are in assembled relation, the intermediate portions 18 nest in the portions 24 and the depressions 16 engage the projections 22 as shown in Figure 4. It is obvious that any relative rotary movement of the two parts is impossible since the angular shoulders on the intermediate portions serve as locks to hold the two parts together.

In order to lock the shell within the cap, one or more projections 26 may be cut in one or more depressed portions 16 of the shell on opposite sides thereof, said projections being` pressed outwardly and extending in a reverse direction from the projections 22 so that when the shell is mounted in the cap, the projections 22 and 26 interlock as shown in Fig. 2. For convenience in unlocking or disengaging the shell from the cap one of the projections 26 or if more than one is used, one group thereof, may be located adjacent the key-slot 14. The shell being of thin metal, the unlocking process may be accomplished as shown in Fig. 3 by pressing inwardly that portion of the shell adjacent to the keyfslot 14 to release the-'projections 26 from thejprojections 22 after which the front portion of the shell -may be drawn downwardly thereby' releasing they .interlocked' projections on the rear sideand permitting the shell to be withdrawn from the cap.

Since the cap is provided with projections around its entire periphery, the shell can be inserted therein in any relative rotary position thereto because the locking projections 26 on the shell may engage any of the proj ections 22 on the cap, thereby obviating the necessity of inserting the shell in any particular position.

In the use of my socket, the shell may be provided witha lining 30 of suitable paper or fibrous material and' within the shell is mounted the usual porcelain which fits snugly therein. This fitting of the porcelain in the shell contributes to the lock between the cap and shell by preventing any bending or inward movement of the shell to permit the cap to be forcibly rotated thereon. `When the porcelain is installed in position the provision -of the angular shoulders in the raised portions between the corrugations on the shell absolutely prevents an relative rotary movement between the shel and cap and makes it impossible to forcibly turn the shell in the'cap thereby resulting in a permanently rigid construction. This is of importance because it prevents the two parts of the socket becoming loose when subj ected to long use and holds the light fixture steady and immovable.

It is to be observed that owing to the simplicity of construction of my mvention, a number of operations now necessary are eliminated and the amount of time and labor consumed in the manufacture is materially decreased enabling me to produce an etlicient socket at a very low cost of production. Since the rojections on the cap are only partially sieared, at their Lupper ends, the cap presents the outer appearance of having a series of depressed squares around its flange which serve as ornamentation and adds to rather than detracts from its attrac tive appearance.

In the foregoing my invention has been described as applied to an electric socket made up of a cap and shell of usual form but this is merely illustrative since it is susceptible of embodiment in various forms of electric fixtures where two members are to be locked together, as for instance, in some types of ceiling or wall `fixtures in which a ,j cap is not vemployed but a ring bands to be construed broadly enough to include a band or similar member mounted on an outlet and adapted to receive another member or shell.

l What I claim is:

1. An electric socket cap having a plain annular imperforateean' e provided with a series of closely associat j equally spaced inwardly extending locking projections hav-l ing Ishoulder portions parallel' with the 1ongitudinal axis of the cap.

2. An electric socket cap having a plain annular imperforate flange provided with a vseries of equally spaced cuts around the same, portions of the flange adjoining said cuts extending inwardly to constitute locking projections having shoulder portions parallel to the longitudinal axis of 'the cap.

3. An electric socket cap having a plain' 4. An electric socket comprising a cap Imember having a plain annular imperforate flange provided with a series of closely assor-ciated equally spaced inwardly extending y locking projections and a shell member having its end provided Withlongitudinal corrugations corresponding in number and arrangement to the series of locking projections on said cap and being provided with two out- Wrdly extending projections onv opposite si es thereof adapted to cooperate with the lockingprojections on said cap to lock said two members together, said locking projections on the cap and the longitudinal corrugations on the shell having enga ing shoulder portions parallel to the longitu inal axis of the shell for preventing relative rotary movement between the parts.

In witness whereof, I hereunto setmy hand this thirty-first day of July 1925.

Y j FRANK E. JOHNSON. 

